This study involves the study of a rechargeable cardiac pacemaker implanted in both dogs and patients. The pacemaker is considered to be permanent with the ability to be recharged after three or four years of use rather than replaced as is the current practice. Accelerated studies have indicated a potential life span of the pacemaker to be in excess of 50 years. Other features include the ability to be noninvasively monitored by use of remote telemetry methods. Research on improved pacemaker electrodes has led to new designs with markedly improved strengths which should help to alleviate many of the existing lead problems. In addition, telemetric transtelephonic multiparameter monitoring system has been applied to a series of lithium powered demanded pacers currently under clinical investigation. BIBLIOGRAPHIC REFERENCES: Hughes, H. C., Brownlee, R. R. and Tyers, G. F. O. Failure of Demand Pacing with Small Surface Area Electrodes. Circulation 54: 128-132, 1976. Brownlee, R. R., Hughes, H. C., Tyers, G.F. O. and Neff, P. H. Monitoring Systems for Cardiac Pacemakers. ASAIO Trans. 23: 1977, in press.